I despise myself for ever being with my ex

I was with her for overall 8 years. She put so much pressure on me, constantly made me feel like I have to save her. A few months into the relationship she made me feel like she'd kill herself if I wasn't there for her when she had some medical issues. If she wasn't in crisis, she made me feel like I'm a horrible person for sometimes asking for a bit of space and began starting fights as soon as we had a little less contact for more than a day when I was somewhere else. Instead of insisting on boundaries, I gave them all up and it got worse and worse until there was no person in me left. After she put me though hell when she had to finish her studies she was done with me and cheated. Before and after she destroyed my mind by gaslighting me to the point where I felt like I was being evil and controlling and didn't know what was real anymore. Then I stayed two more years, still feeling like I needed to help her while she was "trying" to find work.

I only recently really got how messed up she really was and now I realize that I lost my whole life because of her. I will never get over this, I am stuck, I have only suffered with a pathetic excuse of a person and I hate myself for ever thinking she was the only one who could like me. I have been in therapy for the last couple of months but I feel how he thinks that he can't help me. He doesn't really see the severity and it doesn't seem to matter anyway. My life has sucked, I'm a loser and I am old. I have no friends, I have no life and I just don't want to live that joke of existence I have.